Reciprocatory apparatus and energy exchangers therefor



Oct. 16, 1962 J. E. FREEBORN 3,058,361

RECIPROCATORY APPARATUS AND ENERGY EXCHANGERS THEREFOR Filed April 24, 1959 3 Sheets-Sheet 1 Fig. 3a Fig.3b

ISaN 12 k K 1 Wa i Er 420 F i g. 2 F i g 4 F 5 INVENTOR.

James E. Freeborn I BYW 6D A110. neys Oct. 16, 1962 J. E. FREEBORN 3,058,361

RECIPROCATORY APPARATUS AND ENERGY EXCHANGERS THEREFOR Filed April 24, 1959 3 Sheets-Sheet 2 INVENTOR. James E. Freeborn BY J14 63% Attorneys Oct. 16, 1962 J. E. FREEBORN 3,058,361

RECIPROCATORY APPARATUS AND ENERGY EXCHANGERS THEREFOR Filed April 24, 1959 3 Sheets-Sheet 3 IOI I O2 I2 I19 rllllllllll'llln 12/ i 1/2 113 V L Fig. IO

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INVENTOR. James E. Freeborn Attorneys United States Patent Ofilice 3,58,361 Patented Oct. 16, 1962 3,958,361 RECIPROCATORY APPARATUS AND ENERGY EXCHANGERS THEREFOR James Edward Freeborn, Nazeing, England, assignor to Resonated Products, Inc, Yakima, Wash., a corporation of Washington Filed Apr. 24, 1959, Ser. No. 808,804 18 Claims. (CI. 74-26) This invention relates generally to reciprocatory apparatus and energy exchangers therefor.

In the past, in reciprocating apparatus it often has been necessary to limit the frequency and amplitude of the reciprocating parts. This is true because the destructive effects of the forces of inertia seriously limit and restrict the working life, work rates, performance and scope and extent of applications of most reciprocating machines and devices. The forces of inertia cause severe shocks at stroke ends and repeated strain reversals in the reciprocating parts which tend to reduce the fatigue life of the parts. Heretofore, rather than attempting to utilize inertia, attempts have been made to kill or reduce the effects of inertia by providing buffers, dampers, shock absorbers, counterbalancing systems and the like. Such attempts, however, have not been completely successful because of the inability to overcome certain inherent characteristics of all reciprocatory systems. There has been a long felt need for reciprocatory apparatus of the type which can be operated at any desired frequency and amplitude without such destructive efiects.

In general, it is an object of the present invention to provide a reciprocatory apparatus which can be operated at high speeds with increased work output.

Another object of the invention is to provide reciprocatory apparatus of the above character in which the destructive eifects of the inertia forces have been eliminated or minimized.

Another object of the invention is to provide a reciprocatory apparatus of the above character which is more efficient.

Another object of the invention is to provide a reciprocatory apparatus of the above character which is more reliable and in which maintenance time and costs have been reduced.

Another object of the invention is to provide a reciprocatory apparatus of the above character which is relatively inexpensive to manufacture and assemble.

Another object of the invention is to provide a reciprocatory apparatus of the above character in which energy exchangers in the form of elastic storage means are utilized.

Another object of the invention is to provide an energy exchanger of the above character in which the elastic forces are continuously equal and opposite to the inertia forces.

Another object of the invention is to provide energy exchangers of the above character which have high capacity and require a amount of [space and material.

Another object of the invention is to provide reciprocatory apparatus of the above character in which roll type bearings have been utilized to minimize the frictional losses and therefore, wear to the bearings and the journals.

Another object of the invention is to provide reciprocatory apparatus of the above character in which the roll type bearings are simple, inexpensive to fabricate and are sufiiciently rugged to sustain the required heavy semistatic loads imposed upon them.

Another object of the invention is to provide reciprocatory apparatus of the above character in which prestressing is utilized to eliminate lost motion between the moving parts.

Another object of the invention is to provide reciprocatory apparatus of the above character in which prestressing is utilized to prevent strain reversals in the moving parts.

Another object of the invention is to provide reciprocatory apparatus of the above character in which prestressing is utilized to support operating weights.

Another object of the invention is to provide reciprocatory apparatus of the above character in which the rectilinear forces and the rotary torques are balanced within the apparatus.

Additional objects and features of the invention will appear from the preferred embodiments which have been set forth in detail in conjunction with the accompanying drawings.

Referring to the drawings:

FIGURE 1 is an isometric view of a reciprocatory apparatus incorporating the present invention.

FIGURE 2 is an enlarged detail View of one of the energy exchangers utilized in the apparatus shown in FIGURE'I.

FIGURES 3a, 3b, 3c and,3d are schematic illustrations of a roll bearing of the type used in the energy exchanger shown in FIGURE 2 in various positions.

FIGURES 3e, 31 and 3g are vector diagrams of the forces present in the schematic illustrations in FIGURES 3b, 3c and 3d respectively.

FIGURE 4 is an enlarged detail view in cross section of another embodiment of an energy exchanger.

FIGURE 5 is an enlarged detail view in cross section of another embodiment of an energy exchanger.

FIGURE 6 is an isometric view of another embodiment of the present invention.

FIGURE 7 is a side elevational view partly in cross section of still another embodiment of the present invention.

FIGURE 8 is a partial view partly in cross section taken along the line 8-8 of FIGURE 7.

FIGURE 9 is a detail view of the energy exchangers utilized in the apparatus shown in FIGURES 7 and 8.

FIGURE 10 is an illustration showing the method of travel of material in the apparatus shown in FIGURES 7 and 8.

FIGURE 11 is a front elevational view of another embodiment of the invention.

FIGURE 12 is a side elevational view looking along the line 1=212 of FIGURE 11.

FIGURE 13 is a cross sectional view of another energy exchanger suitable for use in reciprocatory apparatus incorporating the present invention.

In general, a reciprocatory apparatus consists of a drive means which has a drive frequency and includes a mass which can take any desired form such as a shaker assembly, a conveyor or any other reciprocating part, and an energy exchanger which is connected to the mass. The energy exchanger or exchangers serve to absorb the kinetic energy from the moving mass and store it in the form of potential energy which, on the return stroke, is transformed from potential energy back into kinetic energy. The energy exchangers have a predetermined relationship to the mass so that the energy exchangers and the mass form a resonant system which has a resonant frequency substantially equal to the drive frequency of the drive means.

One type of reciprocatory apparatus incorporating the present invention is shown in FIGURE 1 of the drawings and consists of a base 11 upon which is mounted a rectangular main frame 12. A pair of energy exchangers 13 and 14 are mounted in the main frame.

Each of the energy exchangers is substantially identical and includes a compliant elastic member which, as shown in FIGURE 2, consists of a tubular torsion member 16 which, if desired, can also be in the form of a torsion rod or other suitable compliant elastic member. One end of the torsion member is provided with an enlarged conical end 16a which is fastened in a cooperating opening in the frame 12 by suitable means such as a press fit so that the end 16a of the torsion member is fixed relative to the main frame 12. The other end of the tubular member is provided with a similar conical surface 160 and is mounted in an opening provided in a lever or torque arm 19 by suitable means such as a press fit so that the torsion member 16 is fixed to the lever arm 19. The torsion member 16 is also provided with a cylindrical journal surface 16d adjacent the conical surface 160 which is adapted to engage the cylindrical race surface 18 of a roll bearing 20 hereinafter described in detail. The race 18 is fixed in the frame or can be an integral part of the main frame as shown in FIGURE 2.

As hereinbefore explained, the tubular torsion member in each of the energy exchangers 13 and 14 is fixed to a lever or torque arm. The torsion member for the energy exchanger 13 is fixed to a lever arm 19, whereas the torsion member for the energy exchanger 14 is attached to a lever arm 21. The lever arms 19 and 21 extend upwardly in a substantially vertical direction and have their ends pivotally connected to support members 22 and 23 which carry a mass 24. These pivotal connections are preferably roll bearings of the kind described herein.

Suitable means is provided for reciprocating the mass rectilinearly and consists of an extension 27 which is formed on the support member 23. A Scotch yoke 28 is connected to the extension 27 which is engaged by a crank arm 29. The crank arm 29 is mounted on a shaft 31 which is adapted to be rotated by any suitable prime mover such as a motor 32.

Operation of this embodiment may now be briefly described as follows: When the motor 32 is operated, shaft 31 is rotated in a clockwise direction as shown. Rotation of the shaft 31 causes the mass 24 to be reciprocated rectilinearly through the action of the Scotch yoke.

When the lever arms 19 and 21 have their upper ends assembled to the support members 22 and 23, the torsion members 16 are rotated equal predetermined amounts. For example, the dotted lines 19a and 21a indicate the position the lever arms 19 and 21 would take if they were disconnected from the supporting members 22 and 23 and the mass 24 removed. It is, therefore, apparent that when the lever arms 19 and 21 are connected to the supporting members 22 and 23, prestress is applied to the affected parts. The amount of prestress should be sufficient so that neither of the individual energy exchangers 13 and 14 reverses its sense of stress or drops to zero torque during reciprocation of the mass 24. The unstressed positions 19a and 21a could as well have outward inclinations as the inward inclinations shown.

It is, however, apparent that the net force exerted on the mass 24 at the position shown in FIGURE 1, that is, mid-position, is zero and increases substantially linearly as the mass 24 moves away from the mid-position in either direction. The net force rate is designed according to formulas well known to those skilled in the art so that the net force from the energy exchangers 1'3 and 14 is always equal to the effect of kinetic force of the mass 24 for the designed speed of operation. Both forces, that is, the force of the kinetic energy from the moving mass 24 and that of the potential energy of the torsion members vary together in opposition. Therefore, as the mass 24 is moved back and forth by the Scotch yoke mechanism, the torsion members are jointly first stressed in one direction and then in an opposite direction. The maximum throw of the stroke or motion is determined by thethrow of the crank arm or member 29.

The energy exchangers 13 and 14 are designed so that the reciprocating apparatus will have a natural resonant frequency at the chosen or designed speed of operation. The net force rates exerted by the energy exchangers 13 and 14 are matched to the chosen mass and its speed of movement in such a way that the sum of the kinetic energy of the reciprocating parts of the system and the potential energy of elastic compliance of the energy exchangers is substantially constant at the predetermined resonant frequency. In calculations, in considering the mass 24, it is necessary to increase it by the equivalents of such minor masses as the levers 19 and 21, the support members 22 and 23, and so forth.

At the resonant frequency of the apparatus, there is periodic inflow and outflow of energy from the energy exchangers which is synchronized with the complementary inflow and outflow of kinetic energy from the reciprocating parts of the apparatus. This synchronized exchange of energy from the energy exchangers to the reciprocating parts requires no energy from the prime mover 32 except for energy required to make up friction and windage losses and energy to perform the actual work which is done by the apparatus. Thus, any external force applied to any parts of the apparatus which tends to reduce its frequency is opposed instantly by the primary drive which resists such change of frequency by an output of energy equal to that demanded at the point of work. In this way, work energy is transmitted without reference to the energy exchangers according to the work demand on the prime mover from the point of work. The energy exchangers, therefore, eliminate cyclic variations which are due to inertia so that only the work demand requires energy from the prime mover. The overall result is a greatly reduced energy demand which can be drawn from a more effectively used energy reserve provided by the prime mover, fliat is, when performing a normally uniform work load, the energy requirements from the prime mover 32 will be determined primarily by the work load and not by inertia effects of the mass of the reciprocating parts.

in other words, resonance occurs when the elastic storage is properly matched to the moving parts for the planned or desired mode of operation of the apparatus so that the sum of the potential energy residing in the elastic storage and the kinetic energy residing in the moving parts is essentially constant. Once resonance has been established, resonance will continue without requiring further energy from the prime mover other than that required for making up the losses from friction, windage and that energy required to perform the useful work. The prime mover need not provide the forces of acceleration and deceleration which are now supplied by the energy exchangers.

In effecting resonance in the aforedescribed apparatus, potential energy is stored by elastic deformation in the energy exchangers 13 and 14 which each include a compliant elastic member. Although the compliant elastic member has been shown to be in the form of a torsion member, other forms of elastic compliance well known to those skilled in the art may be utilized if desired. As shown in FIGURE 2, a tubular torsion member 16 is utilized. Such a member has been chosen because it can be utilized in conjunction with roll bearings 20 hereinbefore described. These bearings have particular advantages in apparatus of this type as hereinafter described.

The torsion member 16 has been provided with enlarged end portions 16a and so that they can be rigidly joined to the parts to which they are afiixed without loss of strength or fatigue life. The enlargements, as shown, are integral parts of the torsion member itself and can be formed in any suitable manner such as by turning the torsion member from solid stock, by upset ting the ends etc. Alternatively, the enlargements may be fabricated separately and be attached by shrink-fitting, welding, etc.

The roll bearings 20 as hereinbefore described consist of a race and a journal rotatably mounted in the race.

As shown in FIGURE 2, the race 18 accommodates the enlarged cylindrical journal surface 16d provided on the torsion member 16. The race 18 can be fabricated in any suitable manner and may be formed of any suitable material such as mild steel. The race 18 in FIGURES l and 2 has been shown to be an integral part of the frame -12 and in the form of a cylindrical hole. However, if

esired, the race can take the form of a portion of a cylinder so that an arcuate surface of a predetermined length is provided. The race is positioned in such a manner that it is concentric with the torsion member 16 as shown schematically in FIGURE 3a. Thus, when no forces are applied to the lever arm 19, the surfaces of the journal 16d and the race 18 are concentric. However, as soon as a small force is applied to the lever arm 19, there is a slight bending which occurs in the torsion member 16 which permits the journal 116d of the torsion member 16 to come in contact with the race 18.

When levers l9 and 21 are connected to the supports 22 and 23, the situation for lever 19 is shown by FIG- URE 3b. Journal surface 16d and race surface 18 are in cont act along a line denoted by point 3612, this line being a common element of the two cylindrical surfaces. The dashed line 37b passes through point 36b and the centers of both elements 16d and 18; and is the common normal to the tangent surfaces. This line extends in the same direction as vector V of FIGURE 3e, which vector is the resultant of vector w, due to the weight of mass 24, and vector p which represents the prestress resulting upon assembly.

When mass 24- is moved during operation to its extreme left position by the Scotch yoke mechanism, lever 19 is inclined leftward, say 10, as shown in FIGURE 30. As a result of the turning or rotation of journal 16d, its new contact point with race 18 is at 36c because of the rolling action. The new normal line 37c extends in a different direction and does not coincide with a force direction line 380 which extends in the same direction as vector v in FIGURE 3f.

Vector v is the resultant of weight w and force p which is the sum of the prestress p and the inertia force of mass 24.

For purposes of illustration, the diameter of journal 16d may be 3/4 that of 18. With this ratio, and the 10 through which arm 19 has moved, it follows that point 3c has moved 30 along the circumference of race 18 from point 345]), as will be explained below. Since v has moved with respect to v the angle between line 380 and line 370 is now about which is safely within a critical angle value of about 22 /2". This critical angle is the frictional angle of slip for the materials of parts 16d and 18, which are here taken, by way of example, to be both mild steel, unlubricated. If the critical angle were exceeded, 16d would slip on 18, rather than rolling as intended.

When the mass 24 is moved to the extreme right position, we have a situation which is shown in FIGURES 3d and 3g. With an assumed 10 movement of the arm from the normal vertical posit-ion, the point of contact 36d has moved approximately from point 36b. The angle between normal line 37a and force direction line 38a is about 9, which is also well within the 22 /2 value. Force direction line 38d extends in the same direction as vector v Vector v is the resultant of the weight w and the force p which is the dilference of the inertia forces and the prestress p The angle between the normal line and the force direction line will therefore always be substantially less than 22 /2 -the critical angle for mild steel on mild steel and hence, a rolling action will occur between the race 13 and the journal 16d rather than slipping during reciprocation of the mass 24- between extreme positions. However, to achieve this condition it is necessary that there be adequate clearance between journal 16d and race 18, in this case provided by the diameter ratio of 3/4.

The action of the journal in rolling in the race may be considered as that of an epicyclic gear train of infinitely many teeth of infinitesimal pitch. If the angle through which the moving member turns be denoted by J, and the angle through which the contact point moves be denoted by B, the relation for the case just considered is:

where b=d /d and d /d is the ratio of the journal diameter to that of the race. With J known from the geometry of the apparatus, and the directions of the resultant vectors v being computed from its dynamics, b must be chosen so that when E is computed by Equation 1, the angle between v and the contact normal will be determined as always safely within the critical angle. The value of b will ordinarily be substantially less than 1, thereby clearly distinguishing a roll hearing from a merely loose rotary bearing. The first minus sign in Equation 1 indicates that B and I change in opposite senses.

It will be appreciated that, if desired, the journal can be made stationary and that the lever arm can be attached to the race and the race rotated with respect to the journal to accomplish the same type of roll contact hereinbefore described. If this is done, the appropriate equation is:

The roll bearings hereinbefore described have been found to be particularly important in the present invention because conventional bearings such as roller and ball bearings are not suitable for this service. The loads which must be supported by the bearings are relatively heavy and almost static. The conventional rotary type bearings of comparable size fail under such loads because of material fatigue caused by local concentration of stresses in absence of the conventional rotation. The roll bearings hereinbefore described are particularly adapted for the semi-static heavy oscillating loads imposed by the hereinbefore described apparatus. Roll bearings have also been found to be particularly satisfactory because they do not require close machining nor do they require meticulous care in fitting and assembling.

The roll bearings also introduce very little friction into the operation of the apparatus because of the rolling action which takes place. Although conventional ball or roller bearings have a rolling action, they have a much smaller load carrying capacity in comparable sizes because the very small diameters of the balls and rollers result in high unit stresses which cause material failure. Extreme fretting also occurs in conventional bearings because of the limited arc of motion utilized in the present apparatus.

It is apparent that by extending axially the surfaces of the journal 16d and the race 18 in the hereinbefore described apparatus, the contact area can be increased substantially so that the bearing can support very heavy loads without excessive unit stress.

Another embodiment of an energy exchanger suitable for use in place of the energy exchangers 13 and 14 as shown in FIGURES l and 2 of the drawing is shown in FIGURE 4. The energy exchanger shown therein has what may be called a re-entrant or folded configuration. It consists of a pair of coaxially aligned torsion members 41 and 42. Both of the members are shown as being tubular; however, it is readily apparent that member 41 can be in the form of a rod if desired.

Torsion member 41 is provided with enlarged end portions 41a and 41b with end portion 41a being fixed in an end portion 42a of the member 42. End portion 41b is fixed to the lever arm 19 in the same manner in which end portion 16c was fixed to the lever arm 19. The torsion member 42 is provided with a cylindrical surface 42b at the end opposite 42a that serves as a race surface which is adapted to accommodate the cylindrical journal surface 41d provided on the torsion member 41.

The torsion member 42 is also provided with a flanged portion 42c which is mounted in the main frame 12 and provides a support for the complete energy exchanger. The other end of the energy exchanger is free relative to the main frame so that torsion forces may be transferred from the member 41 to the member 42.

The operation of this energy exchanger is very similar to that shown in FIGURE 2 except that when force is applied to the lever arm 19, deformation takes place in both of the torsion members 41 and 42, the forces being transferred from the member 41 to the member 42 through the connection provided by the portions 41a and 42a. In this way, it is possible to obtain greater elastic compliance in a given length.

As hereinbefore noted, the initial torsion applied to the torsion member 16 by moving the lever arm 19 from the position 19a to the position shown in FIGURE 1 is designated as prestress. This prestress as hereinbefore explained is sufiicient so that during operation of the energy exchanger, the sense of stress in the torsion member 16 is at no time reversed or drops to zero. The prestress is applied in opposite directions in each of the resonators 13 and 14 so that the net force applied to the mass 24 at the mid position shown in FIGURE 1 is zero.

The use of prestress is particularly advantageous in apparatus of this character because it causes the journals of the energy exchangers to be firmly seated in their races, or if they are already seated because of another effect such as a pendulous weight, the prestressing serves to cause the journals to be more firmly seated.

The use of prestress is also particularly advantageous in that it eliminates lost motion between all of the affected moving parts in the apparatus. The advantage of eliminating such lost motion is readily apparent in that it greatly reduces Wear and tear on the moving parts of the apparatus.

Another advantage is utilizing prestress is that since the strain is not reversed in the torsion members, the fatigue life of the torsion members is prolonged.

In FIGURE 5 is shown another embodiment of an energy exchanger similar to that shown in FIGURE 4 with the exception that the journal portion 211d is formed eccentrically on the torsion member 41 rathar than cencentrically as shown in FIGURE 4. By utilizing such construction, contact occurs between the journal 41d and the race surface 4212 under a zero force condition applied to the lever arm 19. For that reason, the torsion member 41 will not undergo the slight bending which would normally occur if the journal were concentric with the race. It is readily apparent that if it is desired to provide such initial contact on a zero force condition, the race surface 42b can be formed eccentrically instead of a journal 41d to accomplish the same result. When forces are applied to the lever arm, the same rolling action will occur as in the hereinbefore de scribed embodiments of energy exchangers.

In FIGURE 6 is shown another embodiment of reciprocatory apparatus which is similar to that shown in FIGURE 1 except that the mass is arranged to be reciprocated vertically rather than horizontally. As shown the apparatus consists of a base 51 upon which is mounted a main frame 52 substantially identical to the main frame 12. The main frame carries a pair of energy exchangers 53 and 54 similar to the energy exchanger 13 and 14 which are connected to lever arms 56 and 57. The lever arms are pivotally connected to support member 58 and 59 which carry a mass 61. Suitable means is provided for reciprocating the mass 61 Vertically and as shown, can consist of means identical to that provided in FIG- URE l with the exception that it is arranged to provide vertical reciprocation rather than horizontal reciprocation.

In the embodiment shown in FIGURE 1, the mass 24 is supported directly by the lever arms 19 and 21, whereas in the embodiment shown in FIGURE 6, the mass is supported by torque action. The lever arms 56 and 57 rather than having positions which are inclined inwardly as shown in FIGURE 1 for the lever arms 19 and 21, have initial positions which are inclined outwardly as indicated by the dotted lines 56a and 57a. The lever arm 56 has a position which is offset initially a greater angle than the lever arm 57a is otfset initially by an amount which is sufiicient to support the pendulous weight 61. By doing this, the lever arms S and 57 support the pendulous mass and, as shown, can support the pendulous mass so that the lever arms are in a horizontal position when the apparatus is at rest. The same result can be achieved by inclining the unstressed positions 56a and 57a inwardly rather than outwardly, with lever 57 having the greater inclination.

The arrangement of the apparatus shown in FIGURE 6 shows another advantage of prestrcss, that is prestress can be utilized to support operating weights or masses.

The operation of this embodiment of my invention is very similar to that in FIGURE 1 in that, upon operation of the prime mover, the mass 61 will be reeciprocated vertically and as the mass 61 approaches the end of the stroke, the kinetic energy from the mass during deceleraticn will be transferred into the energy exchangers in the form of potential energy by elastic compliance of the torsion members. Upon acceleration from an end of stroke position, the potential energy from the energy exchangers will be transferred into the mass, and so forth.

As hereinbeiore explained, the elastic compliance of the energy exchangers is calculated relative to the mass so that a resonant system is obtained at the designed drive frequency of the prime mover.

It should be pointed out that in constructing the reciprocatory apparatus shown in FIGURES 1 and 2, it is desirable to place the energy exchangers as close as possible to the reciprocating mass because this requires the least strength in the parts for performing the desired work. If, for example, the levers 19 and 2]. served merely to position mass 24 and the elastic storage were located at the distal end of member 27, then member 27 would have to be stronger and heavier, which in turn would mean more mass to resonate. Therefore, by locating the elastic storage means in close proximity to the principal source of kinetic energy, that is, the mass, the strength requirements and weight of the parts are reduced to a minimum.

Another embodiment of the invention is shown in FIG- URES 7 and 8 and consists of a main frame 62 in which are mounted four or more energy exchangers 63. The energy exchangers 63 are shown in detail in FIGURE 9. As will be noted, they are similar to those shown in FIG- URE 2, although other configurations can be used. Each of the energy exchangers consists of a pair of torsion members 73 and '74- which are connected to lever arms 76 and 77, respectively, of equal length. The active ends of parts 74 are mounted in roll hearings in the main frame. The lever 76 have their upper ends connected to one of two counterweights 73, disposed on opposite sides of the tray, whereas the upper ends of the levers 77 are pivotally connected to opposite sides of a tray 79 at points 81. These pivotal connections, as in the other reciprocatory apparatus may be roll bearings. The lever arms 76 and 77 are offset With respect to each other as shown. During assembly, the energy exchangers are subjected to suitable prestress in the manner explained for FIGURES 1 and 6.

Suitable means is provided for reciprocating the tray 79 and the counterweights 78 in an inclined direction and, as shown, can consist of a shaft 86 which is driven by a suitable prime mover such as a motor 87. The shaft is supported by bearing blocks 38 and is provided with two pairs of eccentrics 89. Each pair of eccentrics drives a pair of connecting rods 91 and 92. The connecting rods 91 are pivotally connected to the tray 79 at the points 81,

9 whereas the connecting rods s2 are pivotally connected to the counterweights 78.

The eccentrics are phased 180 apart so that when the tray is moved upwardly and forwardly by the eccentrics 89, the counterweights 78 are moving downwardly and to the rear. The eifective mass of the counterweights and their attachments is made practically equal to that of the trough or tray 79 and its attachments. However, in calculating the mass of the trough, allowance may be made for a part of the average load carried by the trough or tray in its conventional operation.

Operation of the apparatus shown in FIGURES 7, 8 and 9 may now be briefly described as follows. Let it be assumed that it is desired to convey gravel in the trough 79. In FIGURE 10 is a diagram showing the action of the trough upon the pebbles as they are conveyed along the trough. As the trough 79 is moved upwardly and forwardly by the action of the eccentrics 89, the pebbles will be projected in the direction indicated by the line 101. If the travel of the pebble is unimpeded, it will generally follow the direct trajectory which is represented by the parabola 1% shown in FIGURE 10. Thus, each time the trough is lifted upwardly by the eccentrics, the pebbles will be propelled forwardly a predetermined distance depending upon the relative throw of the trough. There will, of course, be some interference between the pebbles, but the general progression will be from left to right as viewed in FIGURE 7.

This apparatus has the same characteristics as the apparatus shown in FIGURES 1 and 6 in that it operates very efiiciently and with resonance. This embodiment, however, incorporates another principle of the present in vention which may be denoted as balance. By balance is meant that the rectilinear and rotary inertia forces are equal and oppositely directed in pairs so that they are confined to the machine. Thus, when the trough is exerting rectilinear inertia force upwardly to the right, the counterweights are exerting an equal force downwardly and to the left as viewed in FIGURE 7 and vice versa. These forces are virtually collinear. Similarly, when the lever arm 77 is torquing clockwise as viewed in FIGURE 7, lever 76 will be torquing counterclockwise, and so forth. Because of this balance, substantially no vibration is transmitted to the surface supporting the framework 62 although there will be a substantially constant push to the left, as viewed in FIGURE 7, due to the acceleration of the load to the right. This force, however, places no great load on the supporting foundation.

On the other hand the machines in the embodiments shown in FEGURES 1 and 6 will transfer their reactions to the foundations and, therefore, the foundations or bases provided must be relatively rugged. This condition can be ameliorated by interposing shock absorbing mounts which convert at least some of the unwanted external energy to lossy forms such as friction. However, external vibrations can be effectively eliminated by utilizing balonce as was done in the apparatus shown in FIGURES 7, 8 and 9, preferably by using twin units operating in phase opposition.

Another embodiment of the invention is shown in FIG- URE 11 in which rotary reciprocation or oscillation is utilized. This embodiment consists of a base 111 which is provided with supports 112 and 112 which carry axially aligned energy exchangers i114 and 116. The energy exchangers are preferably of the type shown in FIGURE 4 in which the flanges 420 are carried by the support members 112 and 113, and in which the outer end of the torsion member 41 is directly connected to the cylindrical mass 119. Upon assembly, the torsion members 114- and 116 are prestressed in opposite directions, as explained for apparatus shown in FIGURE 1, etc.

Suitable means is provided for imparting rotary oscillatory motion to the mass .119 and consists of a lever arm 117 fixed to the mass 119 and extending radially therefrom. A Scotch yoke 1 18 is mounted on the arm 1-17 1% and is engaged on crank arm 12:1 driven by a motor 1122.

Operation of this embodiment of the invention is similar to those hereinbefore described. The mass 119 is reciprocated at a predetermined drive frequency by the motor 122. At this frequency, resonance is obtained with the hereinbefore described advantages. Two masses 119 operated in phase opposition can be used to achieve balance.

In FIGURE 13 is shown another embodiment of an energy exchanger which consists of a torsion member 131 which is provided with enlarged ends 13 1a and 13 1b which are afiixed to lever arms 132 and 133. The torsion member is also provided With journal surfaces 13'1c and 131d which are adapted to engage a pair of race surfaces 136 and 137. The races 136 and 137 as shown can be an integral part of the framework. With this type of an energy exchanger, lever arms can be attached to opposite ends of the energy exchanger and can be rotated in opposite directions to apply stresses to the torsion member. If desired, such a torsion member can be utilized in certain embodiments of the present invention, as for example, the conveying or screening apparatus shown in FIG- URE 7.

It is apparent from the foregoing that I have provide a new and improved reciprocatory apparatus and energy exchangers which can be utilized therefor. The energy exchangers make possible resonant operation of the reciprocatory apparatus because the elastic forces produced by the energy exchangers are continuously equal and opposite to the inertia forces created by the reciprocating mass. The working energies are effectively segregated in the apparatus which serves to reduce the requirements for the prime mover and that of the energy transfer parts. The workless energy is retained within the apparatus and permits control of the external vibration. Stroke end shocks are eliminated and, therefore, fatigue of the machine and the operator are reduced.

The roll type bearings utilized in the energy exchangers and elswhere minimize frictional losses. They are capable of sustaining heavy semi-static loads, and at the same time are simple, rugged and relatively inexpensive to manufacture.

Prestressing is utilized to seat the bearings and to prevent lost motion in the operating parts within the prestressed closed loop. Prestressing also prevents strain reversal and, therefore, prolongs the fatigue life of the operating parts. As also pointed out, prestressing can be utilized for supporting operating Weights.

The energy exchangers have been located in relatively close proximity to the principal inertial mass to minimize the strength and weight of the energy transfer parts of the apparatus. In certain of the apparatuses, rectilinear forces and rotary torques have been balanced so that vibration can be effectively confined to the machine.

This application is a continuation-in-part of application Serial No. 625,153 filed November 29, 1956, now abandoned.

I claim:

1. In reciprocatory apparatus of the type which includes drive means having a drive frequency, a mass and energy exchangers connected to said mass, means adapted to connect said mass to said drive means to impart reciprocating motion to the mass, the mass and the energy exchangers forming a system having a resonant frequency equal to the drive frequency, the energy exchangers having compliant elastic torsion members which receive kinetic energy from the moving mass, store it as potential energy in the form of elastic strain, and return it to the mass as kinetic energy, one end of each of said torsion members being fixed with respect to movement of the mass and the other ends being oscillatable and connected with the mass together with roll hearings on the oscillating ends of the torsion members, the roll bearings comprising journals and races accommodating said journals, the prestressing of the compliant elastic torsion members serving to firmly seat the journals with respect to the races, a rolling action taking place between the journals and the races as the mass is reciprocated.

2. A reciprocatory apparatus as in claim 1 wherein the races are fixed and support the journals and wherein the journals are provided on the moving ends of the torsion members.

3. A reciprocatory apparatus as in claim 1 wherein the journals are fixed and the races are movable with respect to the journals.

4. A reciprocatory apparatus as in claim 1 wherein the reciprocating motion of said mass is within the limits of prestressing said compliant elastic members.

5. A reciprocatory apparatus as in claim 1 wherein the surfaces provided by the journals and the races being arcuate in form, the prestressing of said torsion elements serving to seat the journals with respect to the races, a rolling action occurring between the journals and the races as the torsion members are stressed upon reciprocation of the mass.

6. A reciprocatory apparatus as in claim 5 wherein the arcuate surfaces provided by the cooperating journals and races are concentric with respect to each other before stressing.

7. A reciprocatory apparatus as in claim 5 wherein the arcuate surfaces provided by the cooperating journals and races are eccentric with respect to each other.

8. A reciprocatory apparatus as in claim 5 wherein said mass is reciprocated in a vertical plane and wherein one of said torsion members is stressed an additional amount to support the weight of the mass.

9. In a reciprocatory apparatus, a framework, a mass, a counterweight matched to the mass, means connected to said mass and to said counterweight to impart reciprocating motion to said mass and said counterweight in phase opposition, energy exchanger means mounted in said framework, said energy exchanger means consisting of torsion members and levers, each member having one end fixed in said framework and the other end fixed to a lever, said levers being arranged in pairs with one of the levers of each pair being connected to said mass and the other lever being connected to said counterweight.

10. A reciprocatory apparatus as in claim 9 wherein said torsion members are folded torsion members.

11. A reciprocatory apparatus as in claim 9 wherein the mass and counterweight are disposed so that the rectilinear forces are substantially collinear and opposed.

12. In a reciprocatory apparatus, a framework, a mass, a pair of counterweights matched to the mass and disposed on opposite sides of the mass, means connected to said mass and to said counterweights to impart reciprocating motion to the same in phase opposition, and energy exchanger means mounted in said framework and connected to said mass and said counterweights, said energy exchanger means consisting of torsion members and levers, each of said torsion members having one end fixed in said framework and the other end fixed to a lever, at least one of said levers being connected to said mass and at least one additional lever each being connected to said pair of counterweights.

13. A reciprocatory apparatus as in claim 12 wherein the mass and the counterweights are disposed so that the rectilinear forces are substantially collinear and opposed 12 and wherein the torsion members and the levers connecting the same to the mass and the counterweights are disposed so that the rotary torques are opposed in balanced pairs to thereby confine substantially all vibration within the apparatus.

14. In a reciprocatory apparatus, a framework, a movable mass, driving means having a predetermined drive frequency connected to said mass to impart substantially simple harmonic reciprocatory motion thereto, and a set of energy exchangers mounted on said framework and connected to and normally retaining said mass in a mid position between extremities of movement of the same, each energy exchanger including a lever and a compliant elastic torsion member, one end of the compliant elastic torsion member being fixed to the frame- Work and the other end being movable with respect to the framework, the lever having one end fixed to the movable end of the compliant elastic member and the other end pivotally connected to the mass, and a set of roll bearings mounted in the framework and supporting the movable ends of the compliant elastic members, each roll bearing consisting of a journal and a race having a diameter substantially greater than the diameter of the journal, said set of energy exchangers connected to the movable mass being prestressed in opposite senses to eliminate 10st motion and to hold the journal in continuous engagement with the race so that only a rolling action occurs between the journal and the race, the energy exchangers being chosen so that upon displacement of the mass from the mid position the net force rates exerted by the set of energy exchangers is such that the sum of the kinetic energy of the reciprocating parts and the potential energy of elastic compliance of the energy exchangers -is substantially constant at the drive frequency.

15. Reciprocatory apparatus as in claim 14 wherein said movable mass is movable in a generally vertical direction and wherein one of said energy exchangers is prestressed an adidtional amount to support the Weight of the mass.

16. Reciprocatory apparatus as in claim 14 wherein said compliant torsion member has a folded configuration and consists of a pair of coaxially aligned torsion elements, at least one of the elements being tubular and wherein the race is formed as a part of the tubular member.

17. Reciprocatory apparatus as in claim 14 wherein the journals and the races are substantially concentric before prestressing.

18. Reciprocatory apparatus as in claim 14 wherein the journal is eccentric and is in cont-act with the race before prestressing.

References Cited in the file of this patent UNITED STATES PATENTS 639,028 Garcelon et al. Dec. 12, 1899 1,373,570 Schakel Apr. 5, 1921 1,737,772 Schieferstein Dec. 3, 1929 2,136,951 Overstrom Nov. 15, 1938 2,413,212 Brow-n Dec. 24, 1946 2,534,621 Panhard Dec. 19, 1950 2,638,206 Musschoot et al May 12, 1953 2,942,459 Schilling June 28, 1960 2,947,181 Carrier Aug. 2, 1960 

